Abstract
Several years ago, we designed a particular ray tracing method,
combined with a Hydra parallel code (without baryons)
to compute gravitational CMB anisotropies: weak lensing (WL) and Rees-Sciama (RS) effects.
Only dark matter is essentially necessary to estimate them.
For very small angular scales, we made an exhaustive study leading to a lensing contribution
slightly --but significantly-- greater than previous estimates. Afterwards, the same ray tracing procedure
was included in a parallel Hydra code with baryons. The resulting code was then tested.
